72 巻 (2006) 720 号 p. 1943-1951
In order to investigate the mechanism of noise generation by a train-car gap, which is one of the major noise sources of Shinkansen train, experiments were carried out in a wind tunnel by using 1/5-scaled model train. We measured velocity profiles of the boundary layer that approaches the gap, and it is confirmed that the boundary layer is turbulent. We also measured the power spectrum of noise and surface pressure frustrations around the train-car gap. Peak noise and broad band noise were observed. It is found that strong peak noise is generated when the vortex shedding frequency corresponds to the acoustic resonance frequency determined by the geometrical shape of the gap, and broad band noise is generated at the downstream edge of the gap where vortexes collide. It is estimated that the convection velocity of the vortexs in the gap is approximately 45% of the uniform flow velocity.